Studies have shown that many buildings, for example, tend to be over illuminated by present lighting systems for the purposes required of them. Over illumination in this way results in a wastage of electrical power. Most often fluorescent lights are used in lighting systems for large buildings, for example, in view of their increased efficiency as compared to many other lights. Also, the relationship between light output and power required in a fluorescent light is non-linear, and it has been found that a significant decrease in power usage by fluorescent lights can be achieved without a correspondingly noticeable change in light output in many instances. However, if reduced power is continuously supplied to a fluorescent lighting system, the lights may experience starting difficulties, such as increased flickering time, which can reduce the life span of the lights. Furthermore, it may be desired to adjust the light level output of the lights, and in a large lighting system installation it may be desired to alter the light output or the power consumed thereby from a remote or centralised location.